Liquid crystal displays (LCDs) require a source of high intensity illumination for the images generated on the LCD display panel to be visible to an observer. The panels are customarily illuminated from the sides or from behind the panel, and the panel and illumination system are integrated and embedded together within a single sealed enclosure. This provides a fully functional display system which is suitable for both industrial and consumer use in a wide variety of applications. This is also beneficial as LCDs are being made thinner to use up less real estate.
Multi-Layered display (MLD) systems which employ more than one LCD panel require considerably more illumination than do single panels, due to the limited transmissivity of LCD panels. While a single panel will permit approximately 10% of the incident illumination to reach the observer, use of two panels effectively in series will reduce the transmitted illumination to only 1% (0.10×0.10=0.01=1%). As a result, considerably more illumination is required to achieve satisfactory results. Such lighting dramatically increases the heat generated by both the lighting devices and their supporting electronics and necessitates the use of extreme cooling measures to reduce the temperature of the MLD unit. The performance of the backlighting system has been identified as one of the most critical aspects of MLD design and implementation.